JP5935489B2 - Conveying apparatus, printing apparatus, and conveying method - Google Patents

Description

  The present invention relates to a transport apparatus, a printing apparatus, and a transport method.

  2. Description of the Related Art A conveyance device for driving a conveyance motor to convey an object to be conveyed to a target position is widely used. For example, such a technique is also used for a printing apparatus (for example, an ink jet printer) that transports a transported object to a medium (paper or the like) as a transported object and performs printing on the transported medium. For example, there is a printing apparatus that performs printing on a medium by drawing the medium from a roll body in which a belt-shaped medium is wound in a roll shape. In this case, since the diameter and load of the roll body fluctuate as printing is performed, the accuracy of paper feeding tends to deteriorate. Therefore, for example, in Patent Document 1, the diameter of the roll body is estimated, and control is performed so that the tension (tension) generated in the medium is constant based on the estimation result. In order to keep the tension constant, an adjustment roller (and motor) is installed in front of the paper transport roller (conveyance roller) (upstream in the transport direction) so that the tension between the rollers is constant. Some have been proposed.

JP 2009-242048 A

However, in the case where the adjustment roller is provided and the tension between the rollers is made constant as described above, if the current supply to the motor of the adjustment roller is stopped when the transport roller is stopped, the tension is reduced. There is a possibility that the balance of the medium is disturbed and the stopping accuracy of the medium is deteriorated.
Accordingly, an object of the present invention is to improve the stopping accuracy of a conveyed object.

  The main invention for achieving the above object is to provide a first roller for transporting an object to be transported in a transport direction, a first motor for applying a driving force for rotating the first roller, and the transport direction relative to the first roller. A second roller disposed upstream of the second roller, a second motor for applying a driving force for rotating the second roller, and controlling the first motor to drive the first roller to move the object to be conveyed. A control unit for transporting in the transport direction, wherein the second motor is configured so that a tension generated in the transported object between the first roller and the second roller is constant when the first roller is driven. And a controller that controls torque and generates a predetermined torque in the second motor when the first roller is stopped.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

FIG. 2 is a diagram illustrating an example of an external configuration of a printer. It is a figure which shows the relationship between the drive system which uses DC motor, and a control system. It is a figure which shows the structural example of the external appearance of the rotation holder 31 and the roll motor 33. FIG. FIG. 6 is a diagram illustrating a positional relationship among a sheet P conveyed from a roll body RP, a conveyance roller pair 51, a conveyance adjustment roller pair 61, and a print head 44. 3 is a block diagram illustrating a functional configuration example of a control unit 100. FIG. FIG. 6 is an explanatory diagram schematically showing a configuration of a rotation detection unit 54. 7A and 7B are diagrams for explaining a signal output by the rotation detection unit 54. 3 is a block diagram for explaining a configuration of a speed control unit 120. FIG. 4 is a block diagram for explaining a configuration of a position control unit 140. FIG. It is a figure for demonstrating the target speed with respect to the present position. FIG. 6 is an explanatory diagram regarding control of conveyance of a sheet P by a PF motor 53. It is a figure which shows the time change of the speed of each motor in a comparative example. It is a figure which shows the time change of Duty of each motor in a comparative example. It is explanatory drawing about the conveyance result of the paper P in a comparative example. It is a flowchart which shows the control method of FC motor 63 in this embodiment. It is a figure which shows the time change of the speed of each motor in this embodiment. It is a figure which shows the time change of Duty of each motor in this embodiment. It is explanatory drawing about the conveyance result of the paper P in this embodiment. It is the figure which showed the structural example which can set two roll bodies RP.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A first roller that conveys the object to be conveyed in the conveyance direction, a first motor that applies a driving force to rotate the first roller, and a second roller that is disposed upstream of the first roller in the conveyance direction; A second motor that applies a driving force to rotate the second roller, and a controller that controls the first motor to drive the first roller to convey the object to be conveyed in the conveying direction. The torque of the second motor is controlled so that the tension generated in the conveyed object between the first roller and the second roller during driving of the first roller is constant, and the first roller And a control unit that generates a predetermined torque in the second motor when the motor is stopped.
According to such a transport device, it is possible to suppress disturbance in tension between the first roller and the second roller when the first roller is stopped. Therefore, it is possible to improve the stopping accuracy of the conveyed object.

In this transport apparatus, the second motor is PWM-controlled, and the control unit generates the predetermined torque while maintaining the duty of the second motor when the first roller is stopped. You may make it let it.
According to such a conveying apparatus, the stop accuracy can be easily improved.

In this transport apparatus, the second motor is PWM-controlled, and the control unit performs position feedback of the first motor from speed feedback control at least before the object to be transported reaches the target position. Switching to control may be performed, and the predetermined torque may be generated while maintaining the duty of the second motor after a predetermined time has elapsed since the first motor was switched to the position feedback control.
According to such a conveying apparatus, it is possible to generate a predetermined torque in the second motor without detecting whether or not the first roller has stopped.

In this transport apparatus, the second motor is PWM-controlled, and the control unit holds a duty smaller than the duty of the second motor at the end of tension control to keep the tension constant. A predetermined torque may be generated.
According to such a conveying apparatus, power consumption can be reduced and heat generation can be suppressed.

In such a conveying apparatus, the duty (Duty A) held to generate the predetermined torque in the second motor is the duty (Duty B) at the end of the tension control and the integral subtraction amount N (0 to 128). Using DutyA = DutyB− (DutyB × N) / 128
It is desirable that

In addition, a printing apparatus including the transport apparatus and a printing unit that performs printing on the transported object transported to a target position by the transport apparatus becomes clear.
According to such a printing apparatus, it is possible to improve the stopping accuracy of the conveyed object, so that it is possible to improve the image quality.

  In addition, a first roller that conveys the object to be conveyed in the conveyance direction, a first motor that applies a driving force to rotate the first roller, and a second that is disposed upstream of the first roller in the conveyance direction. A conveyance method using a conveyance device having a roller and a second motor that applies a driving force to rotate the second roller, wherein the first roller is driven by the first motor to convey the object to be conveyed in the conveyance direction. And controlling the torque of the second motor so that the tension generated in the object to be conveyed between the first roller and the second roller is constant during the driving of the first roller. And a second torque generated by the second motor when the first roller is stopped.

=== First Embodiment ===
≪About schematic configuration of printer≫
Hereinafter, an ink jet printer (hereinafter referred to as the printer 10) including a transport apparatus (mainly the control unit 100 and the medium transport mechanism 50) according to an embodiment will be described as an example. Note that the printer 10 of the present embodiment is a printer that can print on a medium having a large size (for example, a printing paper having a size of A2 or more of JIS standard).
In the following description, the lower side refers to the side where the printer 10 is installed, and the upper side refers to the side away from the installed side. Further, a description will be given assuming that the medium supply side is the supply side (rear end side) and the medium discharge side is the paper discharge side (front side).

  FIG. 1 is a diagram illustrating a configuration example of an appearance of a printer 10 according to the present embodiment. FIG. 2 is a diagram illustrating a relationship between a drive system using a DC motor and a control system in the printer 10 of FIG. FIG. 3 is a view showing a configuration example of the outer appearance of the rotary holder 31 and the roll motor 33.

  In this example, the printer 10 includes a pair of leg portions 11 and a main body portion 20 supported by the leg portions 11. The leg portion 11 is provided with a support column 12, and a rotatable caster 13 is attached to the caster support portion 14.

  Various types of internal devices are mounted on the main body 20 in a state of being supported by a chassis (not shown), and these are covered with an external case 21. As shown in FIG. 2, the main body 20 is provided with a roll body drive mechanism 30, a carriage drive mechanism 40, a medium transport mechanism 50, and a transport adjustment mechanism 60 as a drive system using a DC motor. ing.

  The roll body driving mechanism 30 is provided in the roll mounting portion 22 present in the main body portion 20. As shown in FIG. 1, the roll mounting portion 22 is provided on the back side and the upper side of the main body portion 20, and by opening an opening / closing lid 23 that is one element constituting the outer case 21 described above, The roll body RP can be mounted therein, and the roll body RP can be rotationally driven by the roll body driving mechanism 30.

  Moreover, the roll body drive mechanism 30 for rotating the roll body RP has a rotation holder 31, a gear wheel train 32, and a roll motor 33, as shown in FIGS. The rotating holders 31 are inserted from both ends of the hollow hole RP1 provided in the roll body RP, and a pair is provided to support the roll body RP from both ends. A medium (for example, paper P) is wound around the roll body RP, and by rotating the roll body RP, the paper P used for printing is pulled out, and the medium transport mechanism 50 or transport adjustment is performed. Supplied to mechanism 60.

  The roll motor 33 applies a driving force (rotational force) via a gear wheel train 32 to a rotary holder 31 a located on one end side of the pair of rotary holders 31.

  The roll motor 33 can freely change the rotation direction. Hereinafter, the rotation direction of the roll motor 33 when the paper P is fed in the supply direction (hereinafter also referred to as the transport direction) is referred to as a normal rotation direction, and the reverse rotation is referred to as a reverse rotation direction.

  The carriage drive mechanism 40 includes a carriage 41 that is a part of the components of the ink supply / discharge mechanism, a carriage shaft 42, and other carriage motors, belts, and the like (not shown).

  The carriage 41 includes an ink tank 43 for storing ink of each color. The ink tank 43 is fixedly provided on the front side of the main body 20 via a tube (not shown). Ink can be supplied from an ink cartridge (not shown). As shown in FIG. 2, a print head 44 (corresponding to a printing unit) capable of ejecting ink droplets is provided on the lower surface of the carriage 41. The print head 44 is provided with a nozzle row (not shown) associated with each ink, and a piezo element is arranged in the nozzle constituting the nozzle row. By operating the piezo element, it is possible to eject ink droplets from the nozzles at the end of the ink passage.

  The carriage 41, the ink tank 43, the print head 44, a tube (not shown), and an ink cartridge constitute an ink supply / discharge mechanism. The print head 44 is not limited to a piezo drive system using a piezo element. For example, a heater system that heats ink with a heater and uses the generated foam force, a magnetostriction system that uses a magnetostrictive element, and a mist that is controlled by an electric field A mist method or the like may be employed. The ink filled in the ink cartridge / ink tank 43 may be mounted with any kind of ink such as dye-based ink / pigment-based ink.

  FIG. 4 is a diagram illustrating a positional relationship between the paper P conveyed from the roll body RP, the conveyance roller pair 51, the conveyance adjustment roller pair 61, and the print head 44.

  As shown in FIGS. 2 and 4, the medium conveyance mechanism 50 includes a conveyance roller pair 51, a gear wheel train 52, a PF motor 53, and a rotation detection unit 54. The pair of transport rollers 51 includes a transport roller 51a (corresponding to a first roller) and a transport driven roller 51b, and can sandwich the paper P that is drawn from the roll body RP and transported between them. ing.

  The PF motor 53 gives a driving force (rotational force) to the transport roller 51a via the gear wheel train 52. That is, the PF motor 53 corresponds to a motor (first motor) that applies a driving force for rotating the transport roller 51a. As with the roll motor 33, the PF motor 53 can freely change the rotation direction. In the following, the direction of rotation of the PF motor 53 when the paper P is fed in the transport direction is referred to as the forward rotation direction, and the reverse rotation is referred to as the reverse rotation direction.

  In the present embodiment, the rotation detection unit 54 uses a rotary encoder, and includes a disk-shaped scale 54a and a rotary sensor 54b. The rotation detection unit 54 detects the rotation amount of the PF motor 53 (in other words, the transport roller 51a). The details of the rotation detector 54 (rotary encoder) will be described later.

  A platen 55 is provided on the downstream side (sheet discharge side) of the conveyance roller pair 51 in the conveyance direction, and the sheet P is guided on the platen 55 (see FIG. 4). Further, the print head 44 is disposed on the upper side of the platen 55 so as to face the platen 55. A suction hole 55 a is formed in the platen 55. On the other hand, the suction hole 55a is provided so as to be able to communicate with the suction fan 56. When the suction fan 56 is operated, air is sucked from the print head 44 side through the suction hole 55a. Thereby, when the sheet P exists on the platen 55, the sheet P can be sucked and held. In addition, the printer 10 includes other various sensors such as a medium width detection sensor that detects the width of the paper P.

  The configuration of the conveyance adjustment mechanism 60 is substantially the same as that of the medium conveyance mechanism 50, and includes a conveyance adjustment roller pair 61, a gear wheel train 62, an FC motor 63, and a rotation detection unit 64, as shown in FIG. ing. The conveyance adjustment roller pair 61 includes a conveyance adjustment roller 61a (corresponding to a second roller) and an adjustment driven roller 61b, and the paper P drawn from the roll body RP can be sandwiched between them. Yes. The FC motor 63 applies a driving force (rotational force) to the conveyance adjustment roller 61a via the gear wheel train 62. That is, the FC motor 63 corresponds to a motor (second motor) that applies a driving force for rotating the conveyance adjustment roller 61a. As with the roll motor 33, the FC motor 63 can freely change the rotation direction. In the following, the direction of rotation of the FC motor 63 when the paper P is fed in the transport direction is referred to as the forward rotation direction, and the reverse rotation is referred to as the reverse rotation direction. The rotation detection unit 64 is a rotary encoder similar to the rotation detection unit 54, and includes a disk-shaped scale 64a and a rotary sensor 64b. The rotation detection unit 64 detects the rotation amount of the FC motor 63 (conveyance adjustment roller 61a).

  The conveyance adjustment mechanism 60 (conveyance adjustment roller pair 61) is disposed between the roll body RP and the conveyance roller pair 51 (that is, upstream of the conveyance roller 51a in the conveyance direction) and has a function of adjusting the conveyance amount of the paper P. Have. Details of the conveyance adjustment of the paper P will be described later.

  A slack sensor 68 is provided between the conveyance adjustment roller pair 61 and the roll body RP. As shown in FIG. 4, the slack sensor 68 is installed on the lower side of the paper P. The slack sensor 68 is a sensor capable of detecting the vertical position of the paper P (the relative position of the slack sensor 68 and the paper P in the vertical direction) between the conveyance adjustment roller pair 61 and the roll body RP. By using the slack sensor 68, a “sag amount” representing how much slack is obtained with respect to the transport position in the vertical direction when the paper P is transported without being slackened (in a stretched state) is acquired. Can do.

≪About control part≫
FIG. 5 is a block diagram illustrating a functional configuration example of the control unit 100. The control unit 100 receives output signals from the rotation detection unit 54 of the medium conveyance mechanism 50, the rotation detection unit 64 of the conveyance adjustment mechanism 60, the slack sensor 68, and a linear sensor (not shown). In addition, output signals such as a paper width detection sensor, a gap detection sensor, and a power switch for turning on / off the printer 10 (all not shown) are input.

  As shown in FIG. 2, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, a PROM 104, an ASIC 105, a motor driver 106, and the like, which are connected to each other via a transmission path 107 such as a bus. ing. The control unit 100 is connected to the computer COM. The main control as shown in FIG. 5 is performed by cooperation of these hardware and software and / or data stored in the ROM 102 or PROM 104, or by adding a circuit or a component for performing a specific process. The unit 110, the roll motor control unit 111, the PF motor control unit 112, and the FC motor control unit 113 are realized.

  The main control unit 110 controls operations of the roll motor control unit 111, the PF motor control unit 112, and the FC motor control unit 113, and performs a process of transporting the paper P in the transport direction.

  The roll motor control unit 111 controls driving of the roll motor 33 so as to supply (carry) an appropriate amount of paper P to the medium conveyance mechanism 50 of the printer 10 based on the output signal of the slack sensor 68. Specifically, the roll motor control unit 111 controls the roll motor 33 so that the paper P is loosened by a predetermined amount between the roll body RP and the conveyance adjustment roller 61a, and between the roll body RP and the conveyance adjustment roller 61a. The tension is not generated on the paper P.

  The PF motor control unit 112 controls driving of the PF motor 53 based on the output signal of the rotation detection unit 54. Thus, the rotation amount of the transport roller 51a is controlled, and the paper P is transported in the transport direction.

  The FC motor control unit 113 controls driving of the FC motor 63 based on the output signal of the rotation detection unit 64. As a result, the rotation amount of the conveyance adjustment roller 61a is controlled, and the tension (tension) generated on the paper P between the conveyance adjustment roller 61a and the conveyance roller 51a is adjusted as will be described later.

≪About printing operation≫
When the printer 10 receives print data from the computer COM, the control unit 100 controls each unit such as the roll body drive mechanism 30 and the carriage drive mechanism 40 to perform a paper feed process, a dot formation process, a transport process, and the like. .

  The paper feed process is a process of supplying a medium (paper P) to be printed from the roll body RP into the printer 10 and positioning the paper at a print start position (also referred to as a cue position). The control unit 100 rotates the roll body RP in the forward rotation direction and sends the paper P to the conveyance adjustment roller 61a and the conveyance roller 51a. Subsequently, the conveyance adjustment roller 61a and the conveyance roller 51a are rotated to position the paper P sent from the roll body RP at the print start position.

  In the dot formation process, ink is intermittently ejected from the print head 44 that moves along the direction intersecting the conveyance direction of the paper P (hereinafter also referred to as the movement direction) to form (print) ink dots on the paper P. It is processing to do. The control unit 100 moves the carriage 41 in the movement direction, and ejects ink from the print head 44 based on the print data while the carriage 41 is moving. When the ejected ink droplets land on the paper P, dots are formed. On the paper P, a dot line composed of a plurality of dots along the moving direction is formed.

  The transport process is a process of moving the paper P relative to the print head 44 along the transport direction. The controller 100 rotates the transport roller 51a to transport the paper P in the transport direction. By this carrying process, the print head 44 can form dots at positions different from the positions of the dots formed by the previous dot formation process. Control of the feeding amount of the paper P during conveyance will be described later.

  The control unit 100 prints an image on the paper P by alternately repeating the dot formation process and the conveyance process until there is no more data to be printed.

≪About rotation detection unit 54≫
FIG. 6 is an explanatory diagram schematically showing the configuration of the rotation detection unit 54. The rotation detection unit 54 shown in FIG. 6 includes the disc scale 54a and the rotary sensor 54b as described above. The rotary sensor 54 b includes a light emitting diode 541, a collimator lens 542, and a detection processing unit 543. The detection processing unit 543 includes a plurality of (for example, four) photodiodes 544, a signal processing circuit 545, and, for example, two comparators 546a and 546b.

  When the voltage VCC is applied to both ends of the light emitting diode 541 via a resistor, light is emitted from the light emitting diode 541. This light is condensed into parallel light by the collimator lens 542 and passes through the disk-shaped scale 54a. The disk-shaped scale 54a is provided with slits at predetermined intervals (for example, 1/180 inch).

  The parallel light that has passed through the disk-like scale 54a enters each photodiode 544 through a fixed slit (not shown) and is converted into an electrical signal. The electric signals output from the four photodiodes 544 are signal processed in the signal processing circuit 545. The signals output from the signal processing circuit 545 are compared in the comparators 546a and 546b, and the comparison result is output as a pulse. Pulses ENC-A and ENC-B output from the comparators 546a and 546b are output from the rotation detection unit 54.

  7A and 7B are diagrams for explaining a signal output by the rotation detection unit 54. 7A is a timing chart when the PF motor 53 is rotating forward, and FIG. 4B is a timing chart when the PF motor 53 is rotating backward. As shown in the figure, the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees both in the case of forward rotation and reverse rotation of the PF motor 53. When the PF motor 53 is rotating forward, that is, when the transport roller 51a is transporting the paper P in the transport direction, as shown in FIG. 7A, the pulse ENC-A is 90 degrees from the pulse ENC-B. When the phase is advanced by only PF motor 53, the phase of pulse ENC-A is delayed by 90 degrees from pulse ENC-B as shown in FIG. 7B. One cycle T of the pulse ENC-A and the pulse ENC-B is equal to the time during which the PF motor 53 moves (rotates) the slit interval of the disc scale 54a.

≪About PF motor control unit 112≫
The control unit 100 (more specifically, the PF motor control unit 112) of the present embodiment uses such a rotation detection unit 54 (rotary encoder) to perform speed PID control and position by the speed control unit 120 as described later. Position PID control is performed by the control unit 140. In addition, the control by the speed control unit 120 and the position PID control by the position control unit 140 are switched. As will be described later, this switching is performed based on the rotation amount of the transport roller 51a (that is, the current position of the paper P). The speed control unit 120 and the position control unit 140 are configured by the PF motor control unit 112, respectively.

  The PF motor control unit 112 performs control (hold control described later) so as not to move the paper P from the target position when the paper P reaches the target position after switching from the speed PID control to the position PID control. Do more. Hereinafter, a method for controlling the PF motor 53 executed by the PF motor control unit 112 will be described.

  FIG. 8 is a block diagram for explaining the configuration of the speed control unit 120. FIG. 9 is a block diagram for explaining the configuration of the position control unit 140.

  As shown in FIG. 8, the speed control unit 120 includes a position calculation unit 121, a speed calculation unit 122, a first subtraction unit 123, a target speed generation unit 124, a second subtraction unit 125, and a proportional element 126. , An integration element 127, a differentiation element 128, an addition unit 132, and a PWM signal output unit 133. Among these, the position calculation unit 121 counts the edges of the rectangular wave output signal (see FIGS. 7A and 7B) input from the rotation detection unit 54, thereby rotating the rotation amount of the transport roller 51a (in other words, the paper P). Feed amount). When the paper P is transported to the target position, the rotation amount (target rotation amount) of the transport roller 51a for causing the paper P to reach the target position is set in advance.

  The speed calculation unit 122 counts the edges of the rectangular wave output signal input from the rotation detection unit 54. The speed calculator 122 also receives a signal related to time (period) measured by a timer (not shown). Then, the speed calculation unit 122 calculates the rotation speed of the transport roller 51a (feed speed of the paper P) based on the counted edge and time (cycle).

  The first subtracting unit 123 also sets a target position (target rotation of the transport roller 51a for causing the paper P to reach the target position based on the information on the feed amount output from the position calculating unit 121 and the information on the target position. The position deviation is calculated by subtracting the current position (the current rotation amount of the transport roller 51a) from the amount).

  Information on the positional deviation output from the first subtraction unit 123 is input to the target speed generation unit 124. The target speed generation unit 124 refers to the speed profile and outputs information related to the target speed according to the position deviation.

  FIG. 10 is a diagram for explaining an example of the target speed with respect to the current position. In the figure, the target speed output by the target speed generator 124 with reference to the speed profile is shown. Note that a position deviation is input to the target speed generation unit 124, but here the horizontal axis is shown as the current position for easy understanding. That is, when the target speed generation unit 124 outputs the target speed with reference to the speed profile, the target speed having the relationship shown in the figure is output. In the figure, it is shown that control based on the speed PID is performed at a position away from the target position by a predetermined distance. Further, it is shown that control by the position PID is performed at a position within a predetermined distance from the target position. The output target speed is a curve that gradually increases from the start of driving and gradually decreases after maintaining a constant speed.

The second subtraction unit 125 subtracts the current feed speed (current speed) of the PF motor 53 from the target speed, calculates a speed deviation ΔV, and outputs it to the proportional element 126, the integral element 127, and the differential element 128, respectively. The proportional element 126, the integral element 127, and the differential element 128 calculate the following proportional control value QP, integral control value QI, and differential control value QD based on the input speed deviation ΔV.
QP (j) = ΔV (j) × Kp (Expression 1)
QI (j) = QI (j−1) + ΔV (j) × Ki (Expression 2)
QD (j) = {ΔV (j) −ΔV (j−1)} × Kd (Formula 3)
Here, j is time, Kp is a proportional gain, Ki is an integral gain, and Kd is a differential gain.

  The adder 132 adds the control values output from the proportional element 126, the integral element 127, and the derivative element 128, and outputs the sum of the control values obtained by the addition to the PWM signal output unit 133. The PWM signal output unit 133 outputs a PWM signal having a duty ratio obtained by converting the sum of the control values supplied from the adding unit 132.

  The motor driver 106 controls and drives the PF motor 53 by PWM control based on the PWM signal output from the PWM signal output unit 133.

  9, the position control unit 140 includes a position calculation unit 141, a speed calculation unit 142, a first subtraction unit 143, a position gain multiplication unit 144, a third subtraction unit 145, and a proportional element. 146, an integration element 147, a differentiation element 148, an addition unit 152, and a PWM signal output unit 153.

  Among these, the position calculation unit 141, the speed calculation unit 142, the first subtraction unit 143, the proportional element 146, the integration element 147, the differentiation element 148, the addition unit 152, and the PWM signal output unit 153 are included in the speed control unit 120 described above. Since it is the same as the position calculator 121, the speed calculator 122, the first subtractor 123, the proportional element 126, the integral element 127, the derivative element 128, the adder 132, and the PWM signal output unit 134 of the corresponding configuration, Description is omitted.

The position gain multiplication unit 144 is a part that calculates a value obtained by multiplying the position deviation ΔL (= target position−current position) calculated by the first subtraction unit 143 by a predetermined position gain (feedback gain). The third subtracting unit 145 is a part that calculates the deviation ΔH by subtracting the current speed from the value calculated by the first subtracting unit 143. When the position gain is G and the current speed is V, the deviation ΔH is expressed as follows.
ΔH = ΔL (j) × G−V (j) (Formula 4)

≪About control method of PF motor 53≫
A method for controlling the PF motor 53 in the printer 10 having the above configuration will be described below.

  For example, when printing of the printer 10 or the like is performed, if a drive command for the PF motor 53 is issued to the control unit 100, the PF motor 53 is driven according to a target speed as shown in FIG. The control unit 100 (PF motor control unit 112) first controls the PF motor 53 by speed PID control (speed feedback control) using the speed control unit 120. Thereby, the PF motor 53 is controlled by the speed PID control based on the speed deviation ΔV between the target speed and the current speed. That is, the PF motor 53 is driven by speed PID control so as to converge to the target speed shown in FIG. This speed PID control is performed between the acceleration region and the constant velocity region of the PF motor 53, and also in the deceleration region, on the front side of the switching position shown in FIG. 10 (left side: portion indicated by a solid line in FIG. 10). Is done.

  Further, when the PF motor 53 is driven, the control unit 100 always obtains the rotation amount of the transport roller 51a (the current position of the paper P). Based on the current position, the control unit 100 determines whether the paper P has reached a position (switching position) that is a predetermined distance away from the target position (see FIG. 10). In other words, the control unit 100 determines whether or not the rotation amount of the transport roller 51a has reached a rotation amount for reaching the switching position.

  In this determination, when it is determined that the switching position has been reached, the control unit 100 changes from the speed PID control based on the speed control unit 120 to the position PID control (position feedback control) based on the position control unit 140. The control of 53 is switched.

  When the speed PID control is switched to the position PID control, the deviation ΔH is calculated based on (Equation 4). As is clear from this (Formula 4) and the like, the position deviation ΔL gradually decreases as the PF motor 53 is driven after switching. In general, since the PID control is performed so that the deviation becomes 0 (zero), in the above-described position PID control of (Equation 4), if the position deviation ΔL decreases, the position deviation ΔL The current speed for canceling (to zero) will also decrease. Since the control drive based on the speed profile is not performed after switching to the position PID control, in FIG. 10, the relationship between the speed and the position after switching is indicated by a broken line as a virtual one.

  Note that the printer 10 performs position PID control (hold control) in order to prevent the paper P from moving from the target position (stop position) even after the paper P reaches the target position.

  FIG. 11 is an explanatory diagram for controlling the conveyance of the paper P by the PF motor 53. In the figure, the horizontal axis indicates time (t), and the vertical axis indicates the position of the paper P (current position). On the left side of the figure, the PF motor 53 is driven by speed PID control. Thus, the speed PID control reduces the distance between the target position and the current position. Then, when the current position of the paper P falls within a predetermined distance from the target position, the control unit 100 switches the control of the PF motor 53 from the speed PID control to the position PID control. Further, when the control unit 100 determines that the paper P has reached the target position, the control unit 100 switches to hold control and controls the PF motor 53. As described above, the hold control is control for preventing the paper P from being moved from the target position, and is control using a position gain smaller than the position gain of the position PID control before reaching the target position (position PID control). is there.

  As described above, the control unit 100 controls the PF motor 53 so as to approach the target position with the predetermined speed profile by performing the speed PID control when being away from the target position by a predetermined distance. Then, within a predetermined distance from the target position, the control is switched to the position PID control, and the PF motor 53 is controlled so that the paper P reaches the target position accurately (accurately). In this way, the paper P can be accurately reached at the target position. Further, when the control unit 100 determines that the paper P has reached the target position, the control unit 100 performs hold control (position PID control) so as not to move the paper P from the target position.

<About the transport adjustment mechanism 60>
The conveyance adjustment mechanism 60 is provided to generate a certain tension on the paper P before the conveyance roller 51a (upstream side in the conveyance direction). If the transport adjustment mechanism 60 is not provided, the diameter (radius) of the roll body RP is r (cm), and the load of the roll body RP is M (gcm), the paper between the transport roller 51a and the roll body RP. The tension T of P is
T = M / r (Formula 5)
It becomes. Here, when printing is performed by pulling out the paper P from the roll body RP, the diameter r and the load M of the roll body RP change independently. For this reason, it can be seen that it is difficult to control the tension T to be constant.

Therefore, in the printer 10 of the present embodiment, the conveyance adjustment mechanism 60 (conveyance adjustment roller 61a: corresponding to the second roller) is provided between the roll body RP and the conveyance roller 51a (corresponding to the first roller). The control unit 100 performs control (assist) so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant (corresponding to tension control). Here, when the load of the conveyance adjustment roller 61a is Mroll, the diameter (radius) of the conveyance adjustment roller 61a is R, and the assist amount is Matc, the tension T of the paper P between the conveyance roller 51a and the conveyance adjustment roller 61a is ,
T = (Mroll−Matc) / R (Formula 6)
It becomes. Further, from the equation 6, the following equation is obtained.
Matc = Mroll−RT (Formula 7)
In Expression 7, R (the diameter of the conveyance adjustment roller 61a) is constant, and Mroll can be calculated from the measurement. Therefore, Matc for making the tension T constant can be calculated from Equation 7.

  The measurement is a process for obtaining a load when driving the motor (here, the FC motor 63) at a certain speed Vn. For example, after the paper P is set (after the roll body RP is replaced) or printed. Executed before. In the measurement, with the paper P set, the conveyance adjustment roller 61a is rotationally driven in the forward rotation direction at the low speed (Vl) and the high speed (Vh). Then, a load value (specifically a duty value) when driving the FC motor 63 at the speed Vl and a load value (duty value) when driving the FC motor 63 at the speed Vh are calculated. The load Mroll for an arbitrary rotational speed is calculated by linear approximation of the load corresponding to each speed obtained in this way. Then, an assist amount Matc for making the tension T constant can be calculated from the load Mroll. The control unit 100 sets the assist amount Matc using the load Mroll obtained by the measurement in this way.

<< Tension control by the transport adjustment mechanism 60 >>
<Comparative example>
As described above, the control unit 100 (PF motor control unit 112) controls the PF motor 53 based on the speed profile as shown in FIG. In the following description, the control unit 100 controls the PF motor 53 based on the speed profile of only the acceleration region and the deceleration region (the constant speed region is not provided). Further, the control unit 100 switches from the speed PID control to the position PID control before the paper P reaches the target position in the deceleration region. Further, hold control is performed when the paper P reaches the target position.

  The control unit 100 (FC motor control unit 113) controls the FC motor 63 so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant. In this comparative example, in order to reduce power consumption, supply of current to the FC motor 63 is stopped when the transport roller 51a is stopped (that is, the duty of PWM control of the FC motor 63 is set to 0 (zero)). ).

  FIG. 12 is a diagram showing a time change of the speed of each motor in the comparative example, and FIG. 13 is a diagram showing a time change of the duty of each motor in the comparative example.

  In FIG. 12, the horizontal axis indicates time, and the vertical axis (left side) indicates the motor speed. FIG. 12 also shows the change over time of the remaining distance at the conveyance target position of the paper P, and the vertical axis (right side) indicates the remaining distance. In FIG. 13, the horizontal axis represents time, and the vertical axis represents the duty value.

  The control unit 100 (PF motor control unit 112) performs speed PID control so that the PF motor 53 is accelerated from the start of driving to 30 msec. Further, the control unit 100 (FC motor control unit 113) controls the torque of the FC motor 63 so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant. Thereby, for example, as shown in FIG. 12, the speed of the FC motor 63 changes in the same manner as the speed change of the PF motor 53.

  Then, the speed of the PF motor 53 reaches the maximum speed at 30 msec, and thereafter, the speed becomes a deceleration region and the speed decreases. At this time, when the control unit 100 (PF motor control unit 112) switches the control of the PF motor 53 from the speed PID control to the position PID control before the paper P reaches the target position, and further reaches the target position. Switching to hold control (the PF motor 53 is supplied with current for hold control).

  Even in the deceleration range, the control unit 100 (FC motor control unit 113) controls the FC motor 63 so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant. Also here, as shown in FIG. 12, the speed of the FC motor 63 changes in the same way as the speed change of the PF motor 53.

  In the latter half of the deceleration range, the paper P approaches the target position, and the remaining distance becomes smaller as shown in FIG. Then, at about 90 msec, the control unit 100 (FC motor control unit 113) determines that the paper P has reached the target position, and sets the duty to 0 (zero) as shown in FIG. Stop supplying current.

  FIG. 14 is an explanatory diagram of the conveyance result of the paper P in the comparative example. In the figure, control (duty, current speed, target speed) on the PF motor 53 side and time change of the remaining moving distance of the paper P are shown. In the figure, the horizontal axis represents time, the vertical axis (left side) represents Duty, and the vertical axis (right side) represents speed and remaining distance. In FIG. 14, the horizontal axis (time) indicates the same time as in FIGS. 12 and 13.

In this comparative example, as shown in FIG. 13, the supply of current to the FC motor 63 is stopped at about 90 msec when the paper P reaches the target position. On the other hand, as described above, the PF motor 53 is subjected to hold control even after the paper P reaches the target position (current is supplied). For this reason, when the supply of current to the FC motor 63 is stopped, the balance of tension between the transport roller 51a and the transport adjustment roller 61a is disturbed. For example, in FIG. 14, it can be seen that the sheet P returns to the opposite direction of the transport direction in about 90 msec from the remaining moving distance. As described above, in the comparative example, when the paper P reaches the target position (that is, when the transport roller 51a stops), the supply of current to the FC motor 63 is stopped, so that the balance of tension is disturbed, and the paper P is moved to the target position. Can not be stopped accurately.
Therefore, in this embodiment, the accuracy of stopping the paper P is improved.

<This embodiment>
In the comparative example described above, the control unit 100 stops supplying the current to the FC motor 63 when the paper P reaches the target position (when the conveyance roller 51a stops). Even when the paper P reaches the target position, a constant current is supplied to the FC motor 63. More specifically, the control unit 100 (FC motor control unit 113) holds the output duty of the FC motor 63 when the paper P reaches the target position (when the transport roller 51a stops). .

  FIG. 15 is a flowchart showing a method for controlling the FC motor 63 in the present embodiment. Here, it is assumed that the roll body RP is set in the printer 10 and the paper P is positioned at the print start position. That is, the paper P is conveyed between the conveyance roller 51a and the conveyance adjustment roller 61a.

  First, the control unit 100 determines whether the transport roller 51a is driven based on the output of the rotation detection unit 54 (S101). If it is determined that the transport roller 51a is not driven (NO in S101), step S101 is executed again. If it is determined that the transport roller 51a is driven (YES in S101), the control unit 100 (FC motor control unit 113) causes the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a to be constant ( Using the equation (7), the duty value of the FC motor 63 is controlled (S102). Thereby, the rotation of the conveyance adjustment roller 61a is adjusted.

  Thereafter, the control unit 100 determines whether the transport roller 51a has stopped based on the output of the rotation detection unit 54 (S103). If it is determined that the transport roller 51a is not stopped (NO in S103), step S103 is executed again. If it is determined that the transport roller 51a has stopped (YES in S103), the control unit 100 (FC motor control unit 113) holds the duty value of the FC motor 63 when the transport roller 51a is stopped, and keeps the FC motor 63 constant. Generate torque.

  Then, the control unit 100 determines whether or not printing is finished (S105). When it is determined that the printing is finished (YES in S105), the supply of current to the FC motor 63 is stopped, and the control of the FC motor 63 is finished (END). If it is determined that printing has not ended (NO in S105), the determination in step S101 is performed again.

  FIG. 16 is a diagram showing a time change in the speed of each motor in the present embodiment, and FIG. 17 is a diagram showing a time change in duty of each motor in the present embodiment. Each figure shows the speeds and duty values of the PF motor 53 and the FC motor 63 as in the comparative example (FIGS. 12 and 13).

  Also in this embodiment, the control unit 100 (PF motor control unit 112) performs speed PID control so that the PF motor 53 is accelerated from the start of driving to 30 msec. Further, the control unit 100 (FC motor control unit 113) controls the FC motor 63 so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant.

  Then, the speed of the PF motor 53 reaches the maximum speed at 30 msec, and thereafter, the speed becomes a deceleration region and the speed decreases. In this deceleration region, the control unit 100 (PF motor control unit 112) switches the control of the PF motor 53 from the speed PID control to the position PID control before a predetermined distance when the paper P reaches the target position. Further, the control unit 100 (PF motor control unit 112) switches to hold control when the paper P reaches the target position (current for hold control is supplied to the PF motor 53).

  Further, the control unit 100 (FC motor control unit 113) controls the torque of the FC motor 63 so that the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is constant even in the deceleration range (PF). The speed of the FC motor 63 is changing similarly to the speed change of the motor 53).

  As shown in FIG. 16, in the latter half of the deceleration area, the remaining distance becomes smaller because the paper P approaches the target position. Then, the control unit 100 determines that the paper P has reached the target position in about 90 msec.

  In the comparative example (FIG. 13), the supply of current to the FC motor 63 is stopped at this point, whereas the control unit 100 (FC motor control unit 113) of the present embodiment is as shown in FIG. The duty value at this time is held. In other words, the control unit 100 causes the FC motor 63 to generate a constant torque.

  FIG. 18 is an explanatory diagram of the conveyance result of the paper P in the present embodiment. In the figure, similar to the comparative example (FIG. 14), the control (duty, current speed, target speed) on the PF motor 53 side and the time change of the remaining moving distance of the paper P are shown. In the figure, the horizontal axis represents time, the vertical axis (left side) represents Duty, and the vertical axis (right side) represents speed and remaining distance. In FIG. 18, the horizontal axis (time) indicates the same time as in FIGS. 16 and 17.

  In the present embodiment, as shown in FIG. 17, a constant current is continuously supplied to the FC motor 63 even after about 90 msec when the paper P reaches the target position. That is, a constant torque is generated in the FC motor 63. Thereby, when the conveyance roller 51a stops, it can suppress that the balance of tension between the conveyance roller 51a and the conveyance adjustment roller 61a is disturbed, and the paper P can be accurately stopped at the target position as shown in FIG.

  As described above, the printer 10 of the present embodiment includes the transport roller 51a that transports the paper P in the transport direction, the PF motor 53 that applies driving force to rotate the transport roller 51a, and the transport roller 51a in the transport direction. A conveyance adjustment roller 61a provided on the upstream side and an FC motor 63 that provides a driving force for rotating the conveyance adjustment roller 61a are provided.

  When the control unit 100 controls the PF motor 53 to drive the transport roller 51a to transport the paper P in the transport direction, the tension generated on the paper P between the transport roller 51a and the transport adjustment roller 61a is applied. The FC motor 63 is PWM controlled so as to be constant. Further, the control unit 100 holds the duty of the FC motor 63 when the transport roller 51a stops even when the transport roller 51a stops (generates a constant torque).

Thereby, disturbance of the tension between the conveyance roller 51a and the conveyance adjustment roller 61a when the conveyance of the paper P is stopped can be suppressed. Therefore, it is possible to improve the stopping accuracy of the paper P.
In the first embodiment, since the duty value when the transport roller 51a is stopped is held as it is, the stop accuracy can be easily improved.

=== Second Embodiment ===
In the second embodiment, the method for setting the duty of the FC motor 63 at the end of the control for keeping the tension between the transport roller 51a and the transport adjustment roller 61a constant is different from the first embodiment. Since the configuration of the apparatus and the control other than the FC motor 63 control are the same as those in the first embodiment, the description thereof is omitted.

  In the first embodiment, the output duty to the FC motor 63 when the paper P reaches the target position is held, whereas in the second embodiment, the control unit 100 (FC motor control unit 113) After switching from the speed PID control to the position PID control, the duty value after a predetermined time elapses is held. Note that this time measurement is performed based on, for example, a signal (a signal related to the time measured by a timer (not shown)) input to the speed calculation unit 122 described above.

  For example, when 40 msec is set as the predetermined time, in FIG. 17, if switching from the speed PID to the position PID is performed at about 50 msec, 90 msec (after 40 msec from the switching from the speed PID to the position PID) ) Is held. The predetermined time may be reached before the rotation of the transport roller 51a stops, but it is desirable to set the time (predetermined time) so that the predetermined time is reached after the rotation of the transport roller 51a is stopped.

  As described above, in the second embodiment, the duty value after a predetermined time has elapsed after switching from the speed PID control to the position PID control is held. Also in the second embodiment, the stop accuracy can be improved. In the second embodiment, a constant torque can be generated in the FC motor 63 without detecting whether or not the transport roller 51a is stopped.

=== Third Embodiment ===
In the above-described embodiment, the last duty in the control for keeping the tension constant is held as it is, but in the third embodiment, a duty lower than the last duty is held.

  In the third embodiment, the configuration of the apparatus and the control other than the FC motor 63 control are the same as those in the above-described embodiment, and thus the description thereof is omitted.

In the third embodiment, the control unit 100 (FC motor control unit 113) holds a duty smaller than the duty of the FC motor 63 when the paper P reaches the target position. Assuming that the duty to be held is DutyA and the duty when the paper P reaches the target position is DutyB, DutyA is calculated by the following equation.
DutyA = DutyB− (DutyB × N) / 128 (Expression 8)
Here, N is an integral subtraction amount (0 to 128).

  As described above, the Duty (Duty A) smaller than the Duty (Duty B) of the FC motor 63 when the paper P reaches the target position may be held. As the Duty A is smaller, the power consumption can be reduced and the heat generation can be further suppressed. On the other hand, the accuracy of the stop position of the paper P can be improved as the duty A is larger (closer to the duty B).

  In the third embodiment, the duty when the paper P has reached the target position is applied as the duty B. However, as in the second embodiment, the duty B is a predetermined time after switching from the speed PID control to the position PID control. You may use Duty after progress.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
The printer 10 may be a part of a complex device such as a scanner device or a copy device. Furthermore, in the above-described embodiment, the ink jet printer 10 has been described. However, the printer 10 is not limited to an inkjet printer as long as it can print on the medium conveyed to the target position. For example, the present embodiment can be applied to various printers such as a gel jet printer, a toner printer, and a dot impact printer.
A plotter is also included in the printer.

<Control of PF motor 53>
In the above-described embodiment, the speed control unit 120 and the position control unit 140 are each configured to perform PID control. However, the control of the PF motor 53 is not limited to PID control. Control other than PID control includes feedback control such as PI control, PD control, and P control, as well as combined use of feedforward control and feedback control.

<About media>
In the above-described embodiment, the number of roll bodies RP set in the printer 10 is one, but the present invention is not limited to this.
FIG. 19 is a diagram showing a configuration example in which two roll bodies RP can be set.
In the printer shown in the figure, two roll bodies, that is, an upper roll body RPa and a lower roll body RPb can be set. In the drawing, the direction in which the paper P is pulled out from the two roll bodies is indicated by dotted arrows.
As shown in the drawing, the paper P drawn from the roll body (upper roll body RPa or lower roll body RPb) is transported to the transport roller pair 51 via the transport adjustment roller pair 61.

  In addition, since control of each of these rollers and motors is the same as that of the above-mentioned embodiment, description is abbreviate | omitted. In this example, when printing on one roll body RP is completed, printing on the other roll body RP can be performed, and the time required for replacing the roll body RP can be shortened. Also in this case, by performing the same control (tension control) as in the above-described embodiment, it is possible to improve the stopping accuracy of the paper P drawn from each roll body.

  In this embodiment, the paper P wound around the roll body is used as the medium. However, the present invention is not limited to this. For example, it may be plain paper cut to a predetermined size. However, when roll body RP is used like this embodiment, the effect which improves especially stop accuracy can be acquired.

10 printer, 20 main body, 30 roll drive mechanism,
32, gear train, 33 roll motor, 34 rotation detector,
34a disk scale, 34b linear sensor,
40 Carriage drive mechanism, 41 Carriage, 42 Carriage shaft,
43 ink tank, 44 print head, 50 medium transport mechanism,
51 transport roller pair, 51a transport roller, 51b driven roller,
52, gear train, 53 PF motor, 54 rotation detector,
54a disk scale, 54b linear sensor,
60 conveyance adjustment mechanism, 61 conveyance adjustment roller pair, 61a conveyance adjustment roller,
61b driven roller, 62, gear train, 63 FC motor,
64 rotation detector, 64a disk scale, 64b linear sensor,
68 Looseness sensor,
100 control unit, 101 CPU, 102 ROM, 103 RAM,
104 PROM, 105 ASIC, 106 Motor driver,
110 main control unit, 111 roll motor control unit,
112 PF motor control unit, 113 FC motor control unit 120 speed control unit, 121 position calculation unit, 122 speed calculation unit,
123 first subtraction unit, 124 target speed generation unit, 125 second subtraction unit,
126 proportional elements, 127 integral elements, 128 differential elements,
132 addition unit, 133 PWM signal output unit 140 position control unit, 141 position calculation unit, 142 speed calculation unit,
143 1st subtraction part, 144 Position gain multiplication part, 145 3rd subtraction part 146 proportional element, 147 integral element, 148 differential element,
152 adder, 153 PWM signal output unit,
541 LED, 542 collimator lens,
543 detection processing unit, 544 photodiode,
545 signal processing circuit, 546a, 546b comparator

Claims (6)

A first roller that conveys the object to be conveyed in the conveying direction;
A first motor for providing a driving force for rotating the first roller;
A second roller disposed upstream of the first roller in the transport direction;
A second motor for providing a driving force for rotating the second roller;
A control unit for controlling the first motor to drive the first roller to transport the object to be transported in the transport direction, wherein the first roller and the second roller are driven when the first roller is driven. A control unit that controls the torque of the second motor so that the tension generated on the object to be conveyed is constant, and generates a predetermined torque in the second motor when the first roller is stopped; ,
A conveying apparatus comprising: It is a conveying apparatus of Claim 1, Comprising:
The second motor is PWM controlled,
The controller is configured to generate the predetermined torque while maintaining the duty of the second motor at the time when the first roller is stopped. It is a conveying apparatus of Claim 1, Comprising:
The second motor is PWM controlled,
The control unit switches the first motor from speed feedback control to position feedback control at least before the conveyed object reaches a target position, and switches the first motor to the position feedback control. And a duty of the second motor after a predetermined time has elapsed to generate the predetermined torque. It is a conveying apparatus of Claim 1, Comprising:
The second motor is PWM controlled,
The transport unit is configured to generate the predetermined torque while maintaining a duty smaller than a duty of the second motor at the end of tension control in which the tension is constant. A transport apparatus according to any one of claims 1 to 4 ,
A printing unit that performs printing on the transported object transported to a target position by the transport device;
A printing apparatus comprising: A first roller that conveys the object to be conveyed in the conveyance direction, a first motor that applies a driving force to rotate the first roller, and a second roller that is disposed upstream of the first roller in the conveyance direction; A transport method by a transport device having a second motor for applying a driving force for rotating the second roller,
Driving the first roller by the first motor to convey the object to be conveyed in the conveying direction;
Controlling the torque of the second motor so that the tension generated in the conveyed object between the first roller and the second roller during driving of the first roller is constant;
Generating a predetermined torque in the second motor when the first roller is stopped;
A conveying method characterized by comprising: